Hail Mary pass

From Longman Dictionary of Contemporary EnglishHail Mary passˌHail ˈMary pass (also Hail Mary play) noun [countable] American English1in Americanfootball, a long throwforward that you hope will be caught successfully, although it is unlikely, so that your team will score a point when you do not have much time to do this2an action you take that is unlikely to succeed, and which you only take because there is no other way of achieving something